1. Field of the Invention
The present invention relates to an integrated hydroprocessing and fluid catalytic cracking process for production of petrochemicals such as olefins and aromatics from feeds including crude oil.
2. Description of Related Art
Compositions of natural petroleum or crude oils are significantly varied based on numerous factors, mainly the geographic source, and even within a particular region, the composition can vary. Crude oils are refined to produce transportation fuels and petrochemical feedstocks. Typically fuels for transportation are produced by processing and blending of distilled fractions from the crude to meet the particular end use specifications. After initial atmospheric and/or vacuum distillation, fractions are converted into products by various catalytic and non-catalytic processes.
Catalytic processes of hydrocarbon feedstocks are generally categorized based on the presence or absence of hydrogen. Processes including hydrogen, often broadly referred to as hydroprocessing, include, for example, hydrotreating primarily for desulfurization and denitrification, and hydrocracking for conversion of heavier compounds into lighter compounds more suitable for certain product specifications. A typical example of hydroprocessing is the catalytic conversion of hydrocarbon feedstock with added hydrogen at reaction conversion temperatures less than about 540° C. with the reaction zone comprising a fixed bed of catalyst. Although the fixed bed hydrocracking process has achieved commercial acceptance by petroleum refiners, this process has several disadvantages. For example, in order to achieve long runs and high on-stream reliability, fixed bed hydrocrackers require a high inventory of catalyst and a relatively high pressure, i.e., 150 kg/cm2 or greater, to achieve catalyst stability. In addition, two-phase flow of reactants over a fixed bed of catalyst often creates maldistribution within the reaction zone with the concomitant inefficient utilization of catalyst and incomplete conversion of the reactants. Momentary misoperation or electrical power failure can also cause severe catalyst coking which may require the process to be shut down for catalyst regeneration or replacement.
Another type of process for certain hydrocarbon fractions is catalytic conversion without the addition of hydrogen. The most widely used processes of this type are fluidized catalytic cracking (FCC) processes. In an FCC process, a feedstock is introduced to the conversion zone typically operating in the range of about 480-550° C. with a circulating catalyst stream, thus the appellation “fluidized.” This mode has the advantage of being performed at relatively low pressure, i.e., 50 psig or less. However, certain drawbacks of FCC processes include relatively low hydrogenation and relatively high reaction temperatures that tend to accelerate coke formation on the catalyst and requiring continuous regeneration.
In FCC processes, the feed is catalytically cracked over a fluidized acidic catalyst bed. The main product from such processes has conventionally been gasoline, although other products are also produced in smaller quantities, such as liquid petroleum gas and cracked gas oil. Coke deposited on the catalyst is burned off in a regeneration zone at relatively high temperatures and in the presence of air prior to recycling back to the reaction zone.
While individual and discrete hydroprocessing and FCC processes are well-developed and suitable for their intended purposes, there nonetheless remains a need for efficient conversion of a whole crude oil to produce high yield and high quality petrochemicals such as olefins and aromatics.